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The effects of insulin and insulin-like growth factors (IGFs) on ovarian androgen production were examined in ovarian stroma obtained from four women with hyperandrogenism and three women without hyperandrogenism. In incubations of stroma obtained from all four hyperandrogenic patients, insulin alone (500 ng/ml) significantly stimulated androstenedione and testosterone release. LH alone (25 ng/ml) significantly stimulated androstenedione release in incubations of stroma obtained from three of the four hyperandrogenic patients and testosterone release in incubations of stroma obtained from one of the four hyperandrogenic patients. In stromal incubations from three of the four hyperandrogenic patients, insulin alone (500 ng/ml) resulted in a significantly greater release of androstenedione and testosterone than did LH alone (25 ng/ml). Dihydrotestosterone was released in measurable quantities in incubations of stromal tissue obtained from three of the four hyperandrogenic women. In all three instances in which dihydrotestosterone was detectable, insulin alone (500 ng/ml), but not LH alone (25 ng/ml), significantly stimulated dihydrostestosterone release. Incubations of stroma obtained from three nonhyperandrogenic, normally cycling women demonstrated low levels of androstenedione release and negligible testosterone and dihydrotestosterone release. Insulin alone (500 ng/ml) and LH alone (25 ng/ml) produced no significant increase in androstenedione release. Insulin (500 ng/ml) plus LH (25 ng/ml) significantly stimulated androstenedione accumulation in stroma obtained from two of the nonhyperandrogenic women. One insulin dose-response experiment was performed using stromal tissue obtained from a hyperandrogenic woman. In this experiment, insulin, at a dose of 50 ng/ml, was as effective as insulin at a dose of 500 ng/ml in stimulating androstenedione and testosterone release. In addition to insulin, IGF-I/somatomedin C (50 ng/ml) stimulated androstenedione and testosterone release. Relaxin (1 microgram/ml) and multiplication-stimulating activity (50 ng/ml) did not stimulate androstenedione and testosterone release. These studies suggest that human ovarian stroma may be a target tissue for insulin and IGF-I, and that hyperinsulinemia may be an important factor contributing to ovarian hyperandrogenism.

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The concentrations of steroids in antral fluid, the number of granulosa cells, the status of the oocyte, and the diameter of each follicle were determined in human ovaries so that follicles at each stage of the menstrual cycle could be classified as large (greater than or equal to 8 mm diameter) or small (less than 8 mm diameter) and healthy or atretic. The granulosa cells and thecal-enriched tissue from each follicle and the stromal tissue from each ovary were cultured for 6 days in vitro. The amounts of progesterone (P), androstenedione (delta 4), testosterone, dihydrotestosterone, estrone, and estradiol (E2) generated by the different tissues were measured on days 0, 2, 4, and 6 of culture. It was found that granulosa cells, thecal tissue, and stromal tissue all have the biosynthetic capacity to produce P, delta 4, testosterone, dihydrotestosterone, estrone, and E2. No individual steroid-secreting compartment of the ovaries studied, whether part of the follicle or of the stroma, had the exclusive capability of producing any of the above-named steroids at any stage of the menstrual cycle or at any stage of antral follicle growth or atresia. Although the steroids produced by the human follicle appear not to be unique to any one cell type, the patterns of steroidogenesis by the granulosa and thecal compartments differ from one another and from the stroma throughout follicular maturation and atresia. During follicular development, granulosa cells produce large amounts of E2 and small amounts of delta 4. During the preovulatory phase, cells from large follicles (greater than or equal to 8 mm diameter) differentiate from an estrogen-secreting state into a P- and, to a lesser extent, an delta 4-secreting one. By contrast, during follicular atresia, granulosa cells continue to synthesize delta 4, but their capacity to synthesize estrogen is substantially reduced. Furthermore, granulosa cells from atretic follicles are incapable of transforming from an androgen-secreting state into a P-secreting one in tissue culture. During follicular growth, thecal tissue secretes about 2--3 times more delta 4 than E2. By contrast, during follicular atresia, thecal tissue retains its capacity to synthesize delta 4 but loses much of its capacity to synthesize E2. The in vitro capacity of thecal tissue to produce steroids exceeds that of the stroma (on a per weight basis) from 2- to 500-fold. Thecal tissue from healthy but not from atretic follicles is capable of differentiating from an androgen- and estrogen-secreting state to a predominantly P-secreting one in tissue culture. It is postulated that although steroid synthesis may not be rigidly compartmentalized during follicular development, appreciable amounts of the steroids secreted by the granulosa and theca may enter different compartments before leaving the ovary...

Metabolism of [3H]androstenedione was studied in brain tissue homogenates of opossum, bird, snake, sea turtle, urodele amphibian, teleost, shark, skate, hagfish, and lobster. Estrone, 17 beta-estradiol, or 17 alpha-estradiol was formed by central neural tissues of all species, with the exception of the opossum, hagfish, and lobster. Aromatase activity was concentrated in the forebrain, although some estrogen was synthesized by mid- or hindbrain homogenates of two lower vertebrates (teleost and skate) and the newly hatched chick. 5 alpha-Androstanedione (5 alpha-androstane-3,17-dione) or 5 alpha-dihydrotestosterone were products of metabolism in several nonmammalian vertebrates and in the invertebrate central nervous system also. 5 alpha-Reductase was found in all major brain divisions. These and previously reported comparative studies indicate that the ability to aromatize and otherwise transform androgen substrates is a primitive characteristic of the brain that has been widely conserved phylogenetically.

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